Process for molding articles



Patented June 29 1926.

1,590,765 UNITED STATES. PATENT OFFICE.

OSCAR LINDER, OF CHICAGO, ILLINOIS, ASSIGNOR TO IDEAL ROLLER AND MANU- FACTURING 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

rnocnss For. MDLDING ARTICLES.

No Drawing.

to the molding of articles which are made of vulcanized oils such as rollers, platens,

tire-fillers, etc.

It is well known to those skilled in the art that many oils, particularly oils of vegetable origin, such as corn oil, cotton seed oil, lin-- seed oil, rapeseed oil, and soya-bean oil, and also other oils, such as fish oils, etc., can be hardened or solidifiedby vulcanizing them with sulphurchloride, sulphur or other simi lar vulcanizing agents which will convert such oils into a resilient and plastic mass which is somewhat similar to rubber.

A very extensive use of this process is made, for example, in the production of printers and lithographers rollers, in which processthe particular oil used is generally mixed at atmospheric or room temperature with from 10% to 40% of its weight of sulphurchloride, after which the resulting liquid mixture is poured into a suitable mold where it hardens within a few minutes by virtue of the chemical action resulting between the two ingredients into a solid but soft and resilient mass, after which it can be removed from the mold.

The process of making molded vulcanized oil articles, as heretofore practiced, had the great disadvantage in that the resulting mass generally contained gas cells of minute size which rendered the mass somewhat porous and correspondingly ununiform and weak,

" and which also resulted in an uneven surface. Many expedients have been resorted to for the purpose of overcoming this objectionable feature in the vulvanization process, but with no apparent success. The gas cells which occur in the mass are due largely to liberation of acid gases such as hydrochloric acid and sulphur dioxide'during the chemical reaction and at the time when the mass is in the process of hardening, so that these gas cells have no opportunity to escape beforethe mass has hardened.

According to the new process herein described, these gas cells referred to can be eliminated, or, if not entirely eliminated, at least reduced to such a minute size that their presence cannot be readily detected. The improved process consists essentially in subjecting the mass to pressure after it has been poured into the mold at atmospheric or room temperature and while it is undergoing Application filed November 17, 1919. Serial l lo. 338,419.

the process of vulcanization. The mass can be subjected to pressure in a large variety of ways. -Thus, for example, by placing the mold, which contains the liquid mixture of oil and sulphurchloride in a closed receptacle and then subjecting the mass contained in the mold, positioned in the receptacle, to an air pressureof suitable magnitude until the chemical reaction is completed and the mass has hardened as desired. The air pressure is then relieved, the mold removed from K the receptacle, and the molded article removed from the mold. Obviously any other. desired method of applying the pressure to the mass could be readily utilized by those skilled in the art.

v The application of this external pressure to the mass in the mold serves to eifectively prevent the liberation of free gases at least as far as can be determined by optical means; for example, with the help of a microscope and by physical tests, as, for ex; ample, by the determination of the density 1 of the mass. If there are any gas cells in the resulting mass repared in accordance with the teachings oi this invention, they, therefore, must be of such minute size that they cannot be readily detected. The resulting hardened or vulcanized oil, produced according to this process in molded form is much more uniform, stronger, and has a much smoother surface than a corresponding arti- ,cle made without the aid of pressure. The

new process as herein described is, therefore, adapted to be used for the readyinolding of articles which can and could not heretofore be molded satisfactorily by the old process on account of the porosity and the rough surface of the resulting article.

In the place of vulcanization, the oils may be hardened by other processes such as oxidation, hydrogenation, polymerization, etc., with each of which obviously some means of applying pressure to the mass during the periodof vulcanization is utilized, ift'he resulting molded body is to be uniformly solid and resilient and free from apparent porosity or gas and air cells.

For the purpose of preventing the adhesion of the solid mass to the mold and to provide for the ready removal of the molded mass from the mold, the mold isair. The pressure obviously may be of any.

desired amount, so long as it exceeds the atmospheric pressure, but ordinarily and for general purposes a pressure of about 50 pounds per square inch is found to be the most desirable; The pressure may obvious -ly be applied at any time after the unhardened mass has been poured into the mold and before the vulcanization or hard ening has taken place, and said pressure must be kept on continuously until the vulcanizationis completed. As soon as the chemical reaction is completed the pressure can be released, after which thehardened mass may be removedfrom the mold.

Although the oils referred to hereinbefore are mainly and preferably vused with the new process herein described, the process is obviously not restricted specifically to theoils enumerated but may be used with any oil which can be hardened or vulcanized, or any other substance which is liquid at ordinary temperatures and which can be hardened through vulcanization. Likewise,

mixtures of various oils may be used or compounds of oils and varnishes, or any other combinations which canbe readily poured in liquid state at ordinary temperatures. Likewise, in the cold vulcanization process, instead of using pure 'orconcentrated sulphurchloride, a sulphurchloride diluted with any diluent, such as benzol, carbon bisulphide, etc, may be used; Ob-

viously, likewise, any suitable or desirable mixtures of the oil may also be used. While the so-called cold vulcanization takes place without the application of heat, there is -a very slight raise in the temperature due to the chemical reaction.

The invention is obviously not limited to the specific embodiments thereof herein described, but is capable of many variations and other applications within the scope and the-air and gas cells in the article and reducing the size thereof sufliciently so that they will not be detrimental to the finished product.

2. The processof molding resilient articles which consists in vulcanizing oils at room temperature with sulphur chloride under pressure for the purpose of retaining the greater portion of the airand gas cells in the article and reducing the size thereof sufiiciently'so that they will not be detrimental to the finished roduct.

In witness whereof, have hereunto subscribed my name.

' OSCAR LINDER. 

